RESPIRATORY SYSTEM Flashcards
Respiration
assist in gas exchange
- Movement of air into and out of the lungs (Ventilation or Breathing)
- Exchange of O2 and CO2 between the lungs and the blood
- Transport of these gases in the blood
- Exchange of O2 and CO2 between the blood and the tissues
- Cellular respiration: actual use of O2 in the cell (cell metabolism)
Organs of respiratory system
The respiratory system consist of the upper and lower respiratory tract
- Upper respiratory tract: external nose, nasal cavity, pharynx, and associated structures
- Lower respiratory tract: larynx, trachea, the bronchi, and lungs
Functions of the Respiratory System
- Gas exchange (respiratory and cardiovascular systems work together)
- Regulation of blood pH (changing blood CO2)
- Voice production (air moving through the vocal cords)
- Olfaction
- Protection (preventing entry and removing microorganisms from respiratory surfaces)
Nose
- Provides an airway for respiration
- Filters inspired air and cleans it of foreign matter
- Moistens and warms the entering air
- Serves as a resonating chamber for speech
- Houses the olfactory receptors
Consist of the external nose and the nasal cavity
-External nose
only visible structure (cartilage and bone)
-Nasal cavity
-Nares or Nostrils – external openings
-Nasal septum – divides nose into right and left parts
-Choanae – openings to pharynx
-Vestibule – anterior portion of nasal cavity
-Hard palate – separates the nasal cavity from the oral cavity
-Conchae – boney ridges in the nasal cavity
-Meatus – Passageway beneath each conchae
Pharynx (Throat)
About 12.5cm (5 inches) long Mucous membrane lines pharynx Divided into: -Nasopharynx: air only posterior to the choncae and superior to the soft palate Two auditory (eustachian) tubes open here Pharyngeal tonsils or adenoid -Oropharynx: air and food soft palate to the epiglottis Palatine tonsils and lingual tonsils -Laryngopharynx: primarily food and drink epiglottis to the esophagus
Larynx (Voice Box)
Anterior part of the throat, from the base of the tongue to the trachea
The three functions of the larynx are:
-To provide an airway from pharynx to trachea
-To act as a switching mechanism to route air and food into the proper channels
Epiglottis: elastic cartilage that covers the laryngeal inlet during swallowing
Closure of the vestibular and vocal folds
3.To function in voice production
Nine cartilages
-3 unpaired:
Thyroid (shield-shaped)
Cricoid (ring-shaped)
Epiglottis
-6 paired
Cuneiform (wedge-shaped)
Corniculate (horn-shaped
Arytenoid (ladle-shaped)Vocal Cords
Two pairs of ligaments
False vocal cords (vestibular folds)
-Superior mucosal folds
-Have no part in sound production
True vocal cords (vocal folds)
-Inferior mucosal folds composed of elastic fibers
-The medial opening between them is the glottis
-They vibrate to produce sound as air rushes up from the lungs
-Laryngitis: Inflammation of the vocal folds
Trachea (Windpipe)
Function- passageway for air to and from lungs
The mucous membrane lining the trachea is made up of goblet cells and pseudostratified ciliated columnar epithelium
Goblet cells produce mucus
Main Bronchi (Primary)
The most inferior cartilage is carina
It is important radiological landmark
The mucous membrane is very sensitive and materials reaching carina stimulate a powerful coughing reflex
-The right and left bronchi are formed by the division of the trachea
-Right primary bronchus is wider, shorter and more vertical than the left
Common site for an inhaled object to become lodged
-By the time that incoming air reaches the bronchi, it is warmed, cleansed and saturated with water vapor
Lungs
Principal organs of respiration
Base rest on diaphragm and the apex extends superiorly to ~2.5 cm above the clavicle
Right lung has 3 lobes, while the left has only 2 lobes, separated by deep prominent fissure
Lung segments (10/9) are separated by tissue septa, not visible at the surface (can be surgically removed)
Hilus: that part of the lung that is not covered by pleura and through which blood vessels, bronchi, nerves and lymphatics enter and leave the lung
The Tracheobronchial Tree
Terminal bronchioles divide into respiratory bronchioles,→ alveolar ducts→ clusters of alveolar sacs → alveoli
-Alveoli – small air filled chambers where gas exchange between the air and blood takes place
Approximately 300 million alveoli
-Account for most of the lungs’ volume
-Provide tremendous surface area for gas exchange
~7 generations of branching occur from the terminal bronchioles to the alveolar ducts
Once inside the lungs each main bronchus
Subdivides into lobar (secondary) bronchi→
segmental (tertiary) bronchi →giving rise to the bronchioles, which subdivide many times to give rise to the terminal bronchioles
~16 generations of branching from the trachea to the terminal bronchioles
Pulmonary circulation
Blood Supply to Lungs
Lungs are perfused by two circulations: pulmonary and bronchial
Pulmonary circulation
Pulmonary arteries: supply deoxygenated systemic blood to be oxygenated
Ultimately feed into the pulmonary capillary network surrounding the alveoli
Pulmonary veins: carry oxygenated blood from lungs back to the heart
Bronchial circulation
Bronchial arteries: provide systemic oxygenated blood to the lung tissue (from thoracic aorta)
Supply all lung tissue except the alveoli
Bronchial veins: carry the deoxygenated blood back to the heart (drain into azygous vein)
Inspiration, expiration
During increased activity we need more oxygen
Accessory muscles are used to help pull up rib cage to make even larger space in thoracic cavity (inspiration)
Accessory muscles include:
Scalene muscles in neck
Sternocleidomastoid
Pectoralis major
Pectoralis minor
Pulmonary Ventilation (Breathing
Movement of air into the lungs
Inspiration (inhalation): moves air into the lungs
Diaphragm and external intercoastal muscles contract
Expiration (exhalation): movement of air out of the lungs
Abdominal muscles and internal intercoastal muscles contract
Largely a passive process
Muscles of inspiration relax, the rib cage descends due to gravity and the thoracic cavity volume decreases
Pressure changes in the thoracic cavity change air pressure in the lungs, which in turn causes ventilation
largest change in thoracic volume is due to the diaphragm
Lung volumes and capacities
Measurements can be used to -Diagnose disease -Track progress of disease -Track recovery from disease Measurements include -Lung compliance (Resistance) -Pulmonary volumes and capacities -Minute ventilation -Alveolar ventilation
Lung Compliance (Resistance)
Measurement of the ease with which the lungs and thorax expand
Volume increases for each unit of pressure change in alveolar pressure
-Liters (volume of air)/Centimeter of H2O (pressure)
In a normal person = 0.13 L/cm H2O
-Higher than normal compliance = less resistance to lung and thorax expansion (easier to expand the lungs)
Emphysema (destruction of the elastic lung tissue), reduces elastic recoil force of the lung=>easier expansion of the lungs
-Lower than normal compliance = more resistance to lung and thorax expansion (harder to expand)
Pulmonary fibrosis (deposition of inelastic fibers), infant respiratory distress syndrome (collapse alveoli), pulmonary edema, asthma, bronchitis and lung cancer (airway obstruction), deformities as kyphosis and scoliosis)
Pulmonary Volumes
Tidal volume (TV)
-volume of air inspired or expired with each breath (approximately 500 ml at rest)
Inspiratory reserve volume (IRV)
-amount of air that can be inspired forcefully after inspiration of the tidal volume (approximately 3000 ml at rest)
Expiratory reserve volume (ERV)
-amount of air that can be forcefully expired after expiration of the tidal volume (approximately 1100 ml at rest)
-Residual volume (RV)
volume of air still remaining in the respiratory passages and lungs after the most forceful expiration (approximately 1200 ml)
-The TV increases when a person is more active. An increase in TV causes a decrease in IRV and ERV, because the maximum value of respiratory system does not change from moment to moment
Pulmonary Capacities
Sum of two or more pulmonary volumes
-Inspiratory capacity (IC = IRV + TV)
Amount of air that a person can inspire maximally after a normal expiration (approximately 3500mL at rest )
-Functional residual capacity (FRC = ERV + RV)
Amount of air remaining in the lungs after a normal expiration (approximately 2300mL at rest )
-Vital capacity (VC = IRV + TV + ERV)
Maximum volume of air that a person can expel from the respiratory tract after a maximum inspiration (approximately 4600mL at rest )
-Total lung capacity (TLC = IRV + ERV + TV + RV)
Sum of all lung volumes (approximately 5800 ml at rest)
Pulmonary Function Tests
Spirometry is the process of measuring volumes of air that move into and out of the respiratory system
Spirometer – a device used to measure these pulmonary volumes
The following factors can cause variations in Pulmonary Volumes and Capacities
Sex
Age
Body Size
Physical Condition
Pulmonary Function Tests
Normally VC is higher in males, young adults, tall, and thin people
In some conditions, the vital capacity may not be dramatically effected, but how rapidly air is expired can be greatly decreased
Forced expiratory vital capacity
individual inspires maximally and then exhales maximally as rapidly as possible
volume of air expired at the end of the test is the person’s forced expiratory vital capacity
Forced expiratory volume in 1 second (FEV1)
amount of air expired during the first second of the test
decreased FEV1 can be caused by airway obstruction, asthma, emphysema, tumors, pulmonary fibrosis, silicosis, kyphosis, and scoliosis
Minute Ventilation
Minute Ventilation- the total amount of air moved into and out of respiratory system each minute
equals tidal volume (~500mls) times respiratory rate (~12 breaths/min.)
Average ~ 6 L/min
Only measures movement of air into and out of the lungs, not amount of air available for gas exchange
Dead space
Areas of the respiratory system where gas exchange does not take place
Includes the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles (~150 mLs)
Nonfunctional alveoli can also contribute, but are rare in healthy individuals
How do O2 and CO2 are transported in the body
Oxygen Transport by the Blood
1.5% dissolved in the plasma
98.5% carried with Hb inside of RBC’s as oxyhemoglobin
Association of Hb with oxygen is effected by:
pO2-the greater the pO2, the more O2 will combine with Hb, until Hb becomes saturated
Acidity pH-in a lower (more acidic) pH O2 will dissociate from Hb and be released (frequently related to high CO2)
Temperature- as temperature increases, so does the amount of O2 released from Hb
BPG (2,3 biphosphoglycerate)- a chemical formed inside RBC’s during glycolysis- the higher the levels of BPG the more O2 is released by Hb
How do O2 and CO2 are transported in the body
Carbon Dioxide Transport
7% dissolved in plasma
23% carried by Hb as carbaminohemoglobin (HbCO2)
70% converted to bicarbonate (HCO3-) ions
Carbon Dioxide Transport
CO2 diffuses into RBC’s and combines with H2O to form carbonic acid (H2CO3), which quickly dissociates into hydrogen ions and bicarbonate ions
CO2 + H20 Carbonic H2CO3 H+ + HCO3
Anhydrase
Carbon Water Carbonic Hydro Bicar
dioxide acid gen Ion bon
ate
Ion
In RBC’s, carbonic anhydrase reversibly catalyzes the
conversion of CO2 and H2O to carbonic acid
Gas Exchange in the Tissues
- In the tissues, CO2 diffuses into the plasma and into RBC. Some of the CO2 remains in the plasma
- In RBC, CO2 reacts with H2O to form carbonic acid (H2CO3) in a reaction catalyzed by the enzyme carbonic anhydrase (CA)
- Carbonic acid (H2CO3) dissociates to form bicarbonate ions (HCO3-) and hydrogen ions (H+)
- In the chloride shift, as bicarbonated ion HCO3- diffuses out of the RBC, electrical neutrality is maintained by the diffusion of chloride ions (Cl-) into them
5 .Oxygen (O2) is released from hemoglobin (Hb). O2 diffuses out of RBCs and plasma into the tissues - H+ combine with Hb, which promotes the release of O2 from Hb (Bohr effect)
- CO2 combines with Hb. Hb that has released O2 readily combines with CO2 (Haldane effect)
Gas Exchange in the Lungs
- In the lungs, CO2 diffuses from the RBCs and plasma into the alveoli
- Carbonic anhydrase (CA) catalyzes the formation of CO2 and H2O from carbonic acid (H2CO3)
- Bicarbonate ions (HCO3-) and H+ combine to replace H2CO3
- In the chloride shift, as HCO3- diffuse into the RBC, electrical neutrality is maintained by the diffusion of chloride ions (Cl-) out of them
- Oxygen diffuses into the plasma and into RBCs. Some of the O2 remains in the plasma. O2 binds to Hb
- H+ are released from Hb, which promotes the uptake of O2 by Hb (Bohr effect)
- CO2 is released from Hb. Hb that is bound to O2 readily releases CO2 (Haldane effect)
Protective Reflexes
Bronchoconstriction
Irritant receptors
Toxic particles
Irritating particles (i.e. pollen)
Hering-Breuer Reflex prevents over inflation
In infants, it plays an important role in regulating basic rhythm of breathing
In adults, it is important only when the tidal volume is large, such as during heavy exercise
Unconscious reflexes take over voluntary breathing
Effects of Aging
The ability to remove mucus decreases with age
Vital capacity and minute ventilation decreases because of a weakening of respiratory muscles and decreased thoracic cage compliance
Residual volume and dead space increases because of the increased diameter of respiratory passageways. As a result, alveolar ventilation decreases
An increase in resting tidal volume compensates for decreased alveolar ventilation, loss of alveolar walls (surface area), and thickening of alveolar walls
